Toxicological effects of fluazuron on bovine reproductive cells: Implications for fertilization, sperm quality, and oviductal integrity

Fluazuron is a veterinary antiparasitic compound widely used as pour-on in cattle. However, little is known about its potential reproductive toxicity. This study aimed to evaluate the effects of fluazuron on sperm quality, bovine oviduct epithelial cells (BOECs), and bovine in vitro fertilization (IVF). Frozen-thawed sperm were exposed to fluazuron (50 µg/mL) for 2 h and evaluated for motility, mitochondrial activity, and membrane integrity, while BOECs were cultured with fluazuron for 24 h and assessed using MTT and comet assays. IVF was performed with gametes exposed to fluazuron for 18 h to evaluate pronuclear formation, and 24 h to study embryo development. Short-term fluazuron did not significantly affect sperm motility, viability, or membrane function. However, it decreased viability and induced DNA damage in BOECs after 24 h of treatment. Following fluazuron exposure during IVF, no differences were observed between the fluazuron-treated group and the control group in terms of pronuclear formation. However, a significantly higher incidence of abnormally condensed chromatin within the pronuclei was detected in the fluazuron-treated group. Furthermore, embryonic development decreased in both blastocyst and hatching rates in fluazuron treatment. These findings suggest that fluazuron may disrupt early reproductive events through multiple mechanisms, including BOEC dysfunction and chromatin damage. Our results highlight the importance of evaluating reproductive risks associated with antiparasitic drug exposure in livestock.